Glance skeptic and geek head transplant
Good day everyone. The recent publications about head transplants , and especially the phrase from one of them - “In the 1950s, a surgeon from the USSR“ created ”twenty animals with two heads, each of which lived no more than six days, pushed the writing of this article. I really do not want Giktimes turned into a yellow press. Bright title, dubious content and forth. I will try to bring some clarity to this question. Many things are greatly simplified, and some - very much. After all, this is not really a medical resource. So.
The idea of a head transplant has been in the air for a long time. Recall, at least, the novel "The Head of Professor Dowell." From the point of view of the geek, there should be no problems. An artificial heart apparatus exists, that is, it is possible to drive blood through vessels. Nutrient mixtures that can be administered intravenously - also exist. True blood is not only nutrients and water. These are the so-called shaped elements - red blood cells, leukocytes, and platelets. The same erythrocyte lives up to 4 months, so you have to constantly "add" fresh blood. But blood donors are easier to find than body donors. Some problems arise with speech (as Alexander Belyaev noticed) and with food intake. After all, the head is not only to have it, or rather, something else is needed besides the head. True, what is the scientific value of such experiments? Will it turn into a sophisticated torture for the "head"? It is unlikely that a head without a “body” will feel as comfortable as in a futurame.
During the transplantation of the head (as, indeed, of another organ) there are many problems. Some of them are completely solvable, some are not.
The cardiovascular system. At the moment, the technology of working with vessels is well developed. Different types of transplants, intravascular interventions, various methods of damage repair do not cause surprise at the present time. Even operations on the largest vessel of the human body (aorta) are possible. Even in children. Even the heart. The technology is based on stitching vessels using thin needles and threads. The use of artificial grafts is also widespread.
')
Musculoskeletal system. With this, perhaps the least of all problems. Look at professional athletes. Traumatic rupture of biceps, triceps, and pectoral muscles is an unpleasant phenomenon, but not hopeless. Some even return to the sport after similar injuries. After stitching - the muscles grow together. After rupture or separation of tendons - they grow together. True, slower than muscle. Surely, many of the readers of Giktime faced bone fractures and know that the treatment method is quite well developed. The treatment technology is based on ensuring the immobility of bone fragments and time. Immobility can be provided either with metal constructions or plaster. Often, and so, and others.
Nervous system. With this the most difficult. Nerve - can be compared with the cable. Imagine a banal 25 pair cable, increase the number of pairs several dozen (hundreds) times, reduce the diameter of the cable dozens of times - the model of the nerve is in front of you. Increase the number of pairs by an order of magnitude - and get the spinal cord.
The peripheral nerve consists of processes of nerve cells, which are collected in bundles of several hundred pieces. Often they are grouped by type: motor and sensory lie in separate bundles. Dozens of bundles come together in a nerve. Between the bundles are partitions of connective and adipose tissue. When operating without a microscope, you can only sew the outer shell and hope for a miracle. Using a microscope, you can refresh sections and sew each bundle separately. Sections at different ends will be the same and mirrored relative to each other. The beams have small differences in shape and thickness, which allows each beam to find its pair in a different cut. In any case, such interventions require serious equipment and a qualified operating team.
When the peripheral nerve is damaged (intersected), the distal part of the nerve degrades, but the central part slowly begins to grow in the direction of the periphery of the human body. True speed is small - 1-2 millimeters per day. And often they do delayed operations - 2-3 weeks after the injury, so that the distant part of the nerve can degrade so that the central part of the nerve has room to grow. It is possible that the central part of the nerve begins to grow randomly, which can lead to the appearance of phantom pains.
Why it is so important to compare bundles of the crossed nerve, I think obviously. The signal going along the nerve must come to "his" muscle, or take the signal from "his" receptor.
Central nervous system. The cross section of the spinal cord, "butterfly" is familiar to all from the course of school biology. White matter is an analogue of the “pairs” of a conventional UTP cable - neurocyte processes. Gray - the cells themselves are neurocytes.
So, you wanted to move your finger. There are special neurons in a certain part of the cerebral cortex that generate an electrical signal. And they have specialization - some control the upper limb, others - the lower one, etc. The signal propagates along certain bundles (pyramidal paths) down the spinal cord, then along the peripheral nerves to the corresponding muscle.
After crossing, these bundles should be aligned in the spinal cord. Moreover, it is precise enough that the signal from a certain part of the brain should act as before to a certain muscle.
This is not enough. Signals go in the direction of the "head". You pick up something hot - and the signal spreads through the process of the nerve cell to its body, which is in the spinal cord. Then on the process of another nerve cell to its body, which is located in the brain. It is not enough to feel the “signal” warmly or hotly, it is necessary to interpret it, to establish the location, for example, a hand or a leg. Neurons that process this information are also located in the brain. Those who handle from the hands - in one place, which from the legs - in another, and so on.
That is, in order to provide at least some adequate sensitivity, again it is necessary to ensure good accuracy of the connection of the nerve processes.
And it would be okay if the ends of the spinal cord are built one at a time. If the “donor” and “head” are from different people, and they had different TK. The structure of the location of the nerve bundle is very variable. How variable, for example, the course of the vessels. Look at the picture of the saphenous veins on the back of your wrist in your parents. They are similar, but not completely identical. The task in the case of crossing the spinal cord is to find the corresponding bundles and connect them. Even the task of searching for the corresponding bundles is nontrivial, and even more so their “gluing together”. Yes, and how to connect the nerve cells? Sew? Stick together? Today it is a very difficult question.
Ideal TK - a picture from the basic textbook on the anatomy of Sinelnikov Rafail Davydovich. Unfortunately, life is different.
Some people will reasonably object - after all, cut fingers are transplanted. After that, they move and feel. As for movements, one should not forget that the movements of 2-4 fingers are controlled by the muscles on the forearm, that is, if these fingers are damaged, the control of their nervous system is not impaired. The sensitivity is somewhat more complicated. After stitching of the damaged nerve, the slow “germination” of the processes from the central to the peripheral part occurs. And in all this time, the spinal cord and brain adapt to the new "sensations." Sometimes successful, sometimes not.
Others will say - after all, they transplant the heart and, for example, the intestines! And the person then lives, and, sorry, goes to the toilet! Here it is even more interesting - these organs have their own autonomous nervous system. The central nervous system only regulates it. A widespread frame, when the heart is pulled out continues to shrink - not a myth. Despite the fact that you can just as well demonstrate the shrinking intestine, shots with it are not so common. It may be due to the fact that the intestine shrinks much more smoothly and slowly.
There are also many other amusing problems in transplantation. For example, a graft versus host reaction, or, in this case, a “body” against a “head”. When a foreign body enters the body, the body tries to eliminate it. Now imagine that all the blood (which continues to be created in the "body") reveals a very large foreign body. "Head". Fortunately, there are a lot of options to solve this situation. And tested on man. From the suppression of the immunity of the "body" to the selection of the "body" as similar in antigenic composition to the "head" as possible. True drugs suppress immunity, have to be applied for life, but how long will it be in time ...
After transplantation of the “head”, a medical coma will naturally be applied, and after that a completely immobilized body will be obtained. There is another problem. Many of you have seen footage of the conquest of space. The first cosmonauts were simply carried out of the descent vehicles. The hypotrophy of the musculoskeletal system led to spontaneous fractures and the inability to move independently under normal gravity. In this case, the impossibility of normal food intake causes a violation of the motor function of the intestine (constipation). The impossibility of active movements causes stagnant pneumonia. The impossibility of active movements is a general weakening of the musculoskeletal system of the "body". Constant lying in bed leads to the appearance of pressure sores (prolonged nonhealing wounds on the lower parts of the body, which are constantly under pressure, for example, on the buttocks, the coccyx). This is a constant infection, and against the background of immunosuppression, this can be a very big problem. Or it may not be, because the patient’s care will be top notch.
I will not touch upon psychological problems, with your permission. Perhaps they will, but so far there is no way to verify this.
I would also like to clarify who it is - “the surgeon from the USSR” from the 50s. The great man is Vladimir Petrovich Demikhov. Imagine - in the fifties! The country in the postwar period. Suture material cannot even be compared with the current one. There are no drugs that suppress immunity. The same penicillin in the union appeared only in 1942 and a spy story is connected with its appearance. And this man had already transplanted his head from one dog - another. It turned out a dog with 2 heads. These photos spread all over the world. Some dogs from similar experiments lived several weeks! They say that while eating, some heads tried to drive their “neighbors” away from the bowl. True, it looks like ordinary bikes. The authority of Demikhov among the medical community was truly great. Christian Bernard, a South African surgeon who first performed a heart transplant in the world, considered him to be his teacher. Unfortunately, at the end of his life Demikhov fell into disfavor of the authorities, and died in poverty and obscurity. According to one version, he even committed suicide.
At the moment, there is no proven technology to restore the integrity of the damaged spinal cord in humans. It is confirmed in humans! Experiments are constantly being conducted on mice. Including stem cells. Including partly successful. But damage to the spinal cord (complete intersection) in a person is a sentence. Let me assume that transplanting a “head” is only a variant of ill-treatment of people, and news of such a plan is only a reason to popiarit and raise money. Who among readers would agree to be infected with HIV? But the news with bright headlines about the healing constantly flash in the "yellow" media. It is also embarrassing that the “head” transplantation is discussed everywhere, and not the “body” transplant. For me, a “body” transplant is a more adequate term, but this is a completely different story ...
Finally, a video on the topic:
PS .: I wait for the critic in a personal, and the alternative reasoned opinions are in the comments. Thank.
UPD: In connection with the statement by Italian neurosurgeon Sergio Canavero, the professional association of neurosurgeons of Italy issued an official press release . I suggest to get acquainted.
Historical excursion
The idea of a head transplant has been in the air for a long time. Recall, at least, the novel "The Head of Professor Dowell." From the point of view of the geek, there should be no problems. An artificial heart apparatus exists, that is, it is possible to drive blood through vessels. Nutrient mixtures that can be administered intravenously - also exist. True blood is not only nutrients and water. These are the so-called shaped elements - red blood cells, leukocytes, and platelets. The same erythrocyte lives up to 4 months, so you have to constantly "add" fresh blood. But blood donors are easier to find than body donors. Some problems arise with speech (as Alexander Belyaev noticed) and with food intake. After all, the head is not only to have it, or rather, something else is needed besides the head. True, what is the scientific value of such experiments? Will it turn into a sophisticated torture for the "head"? It is unlikely that a head without a “body” will feel as comfortable as in a futurame.
Glance skeptic and geek head transplant
During the transplantation of the head (as, indeed, of another organ) there are many problems. Some of them are completely solvable, some are not.
The cardiovascular system. At the moment, the technology of working with vessels is well developed. Different types of transplants, intravascular interventions, various methods of damage repair do not cause surprise at the present time. Even operations on the largest vessel of the human body (aorta) are possible. Even in children. Even the heart. The technology is based on stitching vessels using thin needles and threads. The use of artificial grafts is also widespread.
')
Musculoskeletal system. With this, perhaps the least of all problems. Look at professional athletes. Traumatic rupture of biceps, triceps, and pectoral muscles is an unpleasant phenomenon, but not hopeless. Some even return to the sport after similar injuries. After stitching - the muscles grow together. After rupture or separation of tendons - they grow together. True, slower than muscle. Surely, many of the readers of Giktime faced bone fractures and know that the treatment method is quite well developed. The treatment technology is based on ensuring the immobility of bone fragments and time. Immobility can be provided either with metal constructions or plaster. Often, and so, and others.
Nervous system. With this the most difficult. Nerve - can be compared with the cable. Imagine a banal 25 pair cable, increase the number of pairs several dozen (hundreds) times, reduce the diameter of the cable dozens of times - the model of the nerve is in front of you. Increase the number of pairs by an order of magnitude - and get the spinal cord.
Peripheral nervous system
The peripheral nerve consists of processes of nerve cells, which are collected in bundles of several hundred pieces. Often they are grouped by type: motor and sensory lie in separate bundles. Dozens of bundles come together in a nerve. Between the bundles are partitions of connective and adipose tissue. When operating without a microscope, you can only sew the outer shell and hope for a miracle. Using a microscope, you can refresh sections and sew each bundle separately. Sections at different ends will be the same and mirrored relative to each other. The beams have small differences in shape and thickness, which allows each beam to find its pair in a different cut. In any case, such interventions require serious equipment and a qualified operating team.
When the peripheral nerve is damaged (intersected), the distal part of the nerve degrades, but the central part slowly begins to grow in the direction of the periphery of the human body. True speed is small - 1-2 millimeters per day. And often they do delayed operations - 2-3 weeks after the injury, so that the distant part of the nerve can degrade so that the central part of the nerve has room to grow. It is possible that the central part of the nerve begins to grow randomly, which can lead to the appearance of phantom pains.
Why it is so important to compare bundles of the crossed nerve, I think obviously. The signal going along the nerve must come to "his" muscle, or take the signal from "his" receptor.
Central nervous system. The cross section of the spinal cord, "butterfly" is familiar to all from the course of school biology. White matter is an analogue of the “pairs” of a conventional UTP cable - neurocyte processes. Gray - the cells themselves are neurocytes.
So, you wanted to move your finger. There are special neurons in a certain part of the cerebral cortex that generate an electrical signal. And they have specialization - some control the upper limb, others - the lower one, etc. The signal propagates along certain bundles (pyramidal paths) down the spinal cord, then along the peripheral nerves to the corresponding muscle.
After crossing, these bundles should be aligned in the spinal cord. Moreover, it is precise enough that the signal from a certain part of the brain should act as before to a certain muscle.
This is not enough. Signals go in the direction of the "head". You pick up something hot - and the signal spreads through the process of the nerve cell to its body, which is in the spinal cord. Then on the process of another nerve cell to its body, which is located in the brain. It is not enough to feel the “signal” warmly or hotly, it is necessary to interpret it, to establish the location, for example, a hand or a leg. Neurons that process this information are also located in the brain. Those who handle from the hands - in one place, which from the legs - in another, and so on.
That is, in order to provide at least some adequate sensitivity, again it is necessary to ensure good accuracy of the connection of the nerve processes.
And it would be okay if the ends of the spinal cord are built one at a time. If the “donor” and “head” are from different people, and they had different TK. The structure of the location of the nerve bundle is very variable. How variable, for example, the course of the vessels. Look at the picture of the saphenous veins on the back of your wrist in your parents. They are similar, but not completely identical. The task in the case of crossing the spinal cord is to find the corresponding bundles and connect them. Even the task of searching for the corresponding bundles is nontrivial, and even more so their “gluing together”. Yes, and how to connect the nerve cells? Sew? Stick together? Today it is a very difficult question.
Ideal TK - a picture from the basic textbook on the anatomy of Sinelnikov Rafail Davydovich. Unfortunately, life is different.
Some people will reasonably object - after all, cut fingers are transplanted. After that, they move and feel. As for movements, one should not forget that the movements of 2-4 fingers are controlled by the muscles on the forearm, that is, if these fingers are damaged, the control of their nervous system is not impaired. The sensitivity is somewhat more complicated. After stitching of the damaged nerve, the slow “germination” of the processes from the central to the peripheral part occurs. And in all this time, the spinal cord and brain adapt to the new "sensations." Sometimes successful, sometimes not.
Others will say - after all, they transplant the heart and, for example, the intestines! And the person then lives, and, sorry, goes to the toilet! Here it is even more interesting - these organs have their own autonomous nervous system. The central nervous system only regulates it. A widespread frame, when the heart is pulled out continues to shrink - not a myth. Despite the fact that you can just as well demonstrate the shrinking intestine, shots with it are not so common. It may be due to the fact that the intestine shrinks much more smoothly and slowly.
There are also many other amusing problems in transplantation. For example, a graft versus host reaction, or, in this case, a “body” against a “head”. When a foreign body enters the body, the body tries to eliminate it. Now imagine that all the blood (which continues to be created in the "body") reveals a very large foreign body. "Head". Fortunately, there are a lot of options to solve this situation. And tested on man. From the suppression of the immunity of the "body" to the selection of the "body" as similar in antigenic composition to the "head" as possible. True drugs suppress immunity, have to be applied for life, but how long will it be in time ...
After transplantation of the “head”, a medical coma will naturally be applied, and after that a completely immobilized body will be obtained. There is another problem. Many of you have seen footage of the conquest of space. The first cosmonauts were simply carried out of the descent vehicles. The hypotrophy of the musculoskeletal system led to spontaneous fractures and the inability to move independently under normal gravity. In this case, the impossibility of normal food intake causes a violation of the motor function of the intestine (constipation). The impossibility of active movements causes stagnant pneumonia. The impossibility of active movements is a general weakening of the musculoskeletal system of the "body". Constant lying in bed leads to the appearance of pressure sores (prolonged nonhealing wounds on the lower parts of the body, which are constantly under pressure, for example, on the buttocks, the coccyx). This is a constant infection, and against the background of immunosuppression, this can be a very big problem. Or it may not be, because the patient’s care will be top notch.
I will not touch upon psychological problems, with your permission. Perhaps they will, but so far there is no way to verify this.
I would also like to clarify who it is - “the surgeon from the USSR” from the 50s. The great man is Vladimir Petrovich Demikhov. Imagine - in the fifties! The country in the postwar period. Suture material cannot even be compared with the current one. There are no drugs that suppress immunity. The same penicillin in the union appeared only in 1942 and a spy story is connected with its appearance. And this man had already transplanted his head from one dog - another. It turned out a dog with 2 heads. These photos spread all over the world. Some dogs from similar experiments lived several weeks! They say that while eating, some heads tried to drive their “neighbors” away from the bowl. True, it looks like ordinary bikes. The authority of Demikhov among the medical community was truly great. Christian Bernard, a South African surgeon who first performed a heart transplant in the world, considered him to be his teacher. Unfortunately, at the end of his life Demikhov fell into disfavor of the authorities, and died in poverty and obscurity. According to one version, he even committed suicide.
Total
At the moment, there is no proven technology to restore the integrity of the damaged spinal cord in humans. It is confirmed in humans! Experiments are constantly being conducted on mice. Including stem cells. Including partly successful. But damage to the spinal cord (complete intersection) in a person is a sentence. Let me assume that transplanting a “head” is only a variant of ill-treatment of people, and news of such a plan is only a reason to popiarit and raise money. Who among readers would agree to be infected with HIV? But the news with bright headlines about the healing constantly flash in the "yellow" media. It is also embarrassing that the “head” transplantation is discussed everywhere, and not the “body” transplant. For me, a “body” transplant is a more adequate term, but this is a completely different story ...
Finally, a video on the topic:
PS .: I wait for the critic in a personal, and the alternative reasoned opinions are in the comments. Thank.
UPD: In connection with the statement by Italian neurosurgeon Sergio Canavero, the professional association of neurosurgeons of Italy issued an official press release . I suggest to get acquainted.
Source: https://habr.com/ru/post/374927/
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